The Limits Of Reductionism John Miller Ritchie LSE M. Phil Thesis UMI Number: U105058 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a complete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. Dissertation Publishing UMI U105058 Published by ProQuest LLC 2014. Copyright in the Dissertation held by the Author. Microform Edition © ProQuest LLC. All rights reserved. This work is protected against unauthorized copying under Title 17, United States Code. ProQuest LLC 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106-1346 7 UU-O / r * O N *W 1V3W TCW ^c?439 7 ABSTRACT The central claim of this thesis is that physicalism is not well supported by our scientific knowledge. The argument splits into four sections. In section I, I argue that given the current state of science a reductive version of physicalism cannot be maintained, if theoretical reductions are thought to be obtainable in practice. In section II, I argue that physicalists who are realists about higher-order properties are committed to reduction in principle of these properties to physics. In section III, I argue that one of the core elements of physicalist philosophy, the completeness of physics, is highly questionable in light of certain features of quantum theory. In the final section, I survey a range of possible alternatives ontologies to physicalism and argue for a pluralistic ontology. 2 CONTENTS Introduction...................................................................... P.4 Section I: The Limits of Reduction................................ P.8 Section II : Physicalism and Reduction in Principle...P.28 Section II: Quantum Quandries.................................... P.50 Section IV: Emergent Alternatives.............................. P.68 Conclusion..................................................................... P. 87 Bibliography...................................................................P.90 INTRODUCTION Physicalism is an ontological thesis. In its broadest and most general sense, it claims that physical “stuff’ and physical properties constitute the whole world.1 Physicalism is the philosophical orthodoxy in all matters metaphysical. It is a view that dictates the nature of research which many philosophers pursue, whether it be in the philosophy of mind, the philosophy of science or some other discipline. However, 1 take it that physicalism is not a doctrine which is intuitively obvious. It is presumably a position that can be doubted and hence must be argued for. There are good ways and bad ways in which this might be done. We might consider a few of the bad ways first.2 Some physicalists might claim that their ontological position is motivated by simplicity or elegance - philosophical good taste decrees we should avoid the messy world of pluralistic ontologies. I do not find that argument remotely convincing. I do not see any a priori reason why God should have fashioned the world for Stoics rather than Epicureans. However, even if we do suppose it is a reasonable argument, it must have as much (or as little) force in the mouth of any other monistic philosopher. Why couldn’t an idealist equally well claim his ontology was the simplest? A good argument for physicalism must have more bite. Another argument physicalists might proffer is that only physicalism wards off philosophical disreputables - that is, “spooky” properties like Cartesian souls. But again I can not see why such a line of argument should persuade anyone. After all, what is a spooky property? Are the exotic properties of subatomic particles - spin, strangeness, charm - spooky? Certainly they are much less familiar than the sorts of properties non-physicalists might claim are not actually physical, viz. intentional properties. Indeed, it seems clear that what one does or does not decree spooky is 11 take it that physicalists can remain neutral on certain questions, for example the existence of abstract objects such as numbers. 2 The arguments I present here are anaemic versions of the summary of possible reasons John Haugeland, [1984] provides for phyicalism. Of course, I do not suggest that Haugeland himself finds such arguments, even in their full-blodded form, convincing. 4 usually decided after one has adopted a particular ontological position. Berkeley, for one, found incomprehensible the idea that inert matter could cause anything. For him materialism, the ancestor of physicalism, was a spooky theory. Spookiness, by physicalist lights, then does not appear to mean much more than non-physical; and while it is true that physicalism is the philosophical position which guards against the non-physical, that statement, by itself, is unlikely to have much persuasive force. Any self-respecting physicalist should be embarrassed by these arguments. The real motivation for physicalism must come from somewhere else or one could not account for the widespread acceptance of the view within the philosophical community. I think what really drives the physicalist consensus is a deep respect for the natural sciences. In fact, I think physicalism has its roots in two other philosophical positions: scientific realism and naturalism. Scientific realism is the doctrine which asserts the way science describes the world is true or nearly true. Naturalism has a technical usage in philosophy associated with Quine: in essence it involves the denial of a priori knowledge. However, I use the term here in a much broader sense. I take naturalism to be the attitude that we should seek within the natural sciences for answers to our philosophical questions and we should judge our philosophically favoured theories against what the natural sciences say. One does not need to look hard to find physicalists proclaiming allegiance to both these views: Materialist metaphysicians wish to side with physics (Lewis [1983], p.364) Broadly empirical in character, they [physicalist claims] are supported inductively by scientific practice. (Heilman and Thompson [1977], p.311) According to contemporary physicalists, the principles of physicalism are to be treated as high- level empirical hypotheses or generalizations...If phenomena turn up which resist a naturalist 5 account even after years of trying, then the physicalists principles should be rejected or revised. (Post, J. [1991] p.75) None of these quotes of course offer actual arguments, only intentions. But if these intentions could be realised, if physicalists could argue from the sciences to their favoured ontological position, that would be a powerful consideration in their favour. Such an argument might take a number of forms. The most complete form of justification from science would be to show that the physics does actually explain all the events of the universe. In other words, if we could show that all true theories reduced to physics, then we would know that physicalism is true. This has not been done. A close second as a way of motivating physicalism would be to show that given the state of science, we should expect reductions of other scientific disciplines to physics. This is an historically important position, associated with the so-called unity of science programme. If it were feasible it would provide strong grounds for being a physicalist. However, I shall show in section I that the current state of science cannot support the reductive programme. A still less ambitious means of arguing for physicalism would eschew the possibility of actual theoretical reductions. Indeed, this view, what is called non- reductive physicalism, is probably the most popular version of physicalism touted by philosophers today. Such physicalists will have to provide some explanation of what the relation between physics and the other sciences is, if it is not reductive. They will also need to show, if they wish to claim their physicalism has naturalistic roots, that they have some argument for physicalism which emerges from physics itself.3 I shall argue that neither of these aims can be achieved. In section II, I shall demonstrate that non-reductive physicalists, insofar as they are physicalists, are committed to reductions in principle. Section III will argue that if we take current physics itself at all 3 This argument will of course apply equally to those who call themselves eliminativists 6 seriously it, if anything, undermines physicalism, rather than lending it support. These arguments will not refute physicalism but they should persuade the reader that physicalism has little support from the natural sciences. By rejecting physicalism, though, we need not reject the realist or naturalist pillars on which it is built. In fact, it will be my contention in the final section that we can build an ontology that is not physicalistic but is still in keeping with the idea that our metaphysical views should emerge from our scientific theories. Hence, it will be this view rather than physicalism that has the honour of being scientifically respectable. 7 THE LIMITS OF REDUCTION The issue we are concerned with here is theoretical reduction. Or to put it another way, when does one theory reduce to another? We are interested in theoretical reduction inasmuch as it is a motivation for physicalism. The reductionist hopes to be able to explain bigger things in terms of smaller things. He hopes to account for humans (and other animals) in terms of biology, biology in terms of chemistry and chemistry in terms of physics. The ideal end for someone who advocates reductionism as a means of formulating their physicalist views is that all non-physical theories should be explicable in terms of the one fundamental theory, physics (or microphysics). It will be my task to demonstrate that actual reductions between various sciences are unlikely, or impossible. Thus physicalism cannot be argued for as a corollary of the unity of science programme. This section splits broadly into two sub-sections. The first sub-section is concerned mainly with what a reduction is. I shall argue that we have no good formal account of theoretical reduction.